This invention relates to multi-chamber dispensers for viscous substances that are adapted to receive sets of refill chambers. More particularly, it relates to the dispensing of two or more substances that are not storage stable and thus cannot be contacted or mixed until the time of use.
There is a need in the dental care area for the delivery of two or more substances that are reactive with each other or which to some degree are not storage stable in the presence of each other. This problem is solved by the use of a multi-chamber dispenser where the substances do not contact until dispensed. Examples of such substances are baking soda and various peroxide yielding materials and stannous fluoride and pyrophosphate compounds. There are yet other substances that advantageously are applied to teeth and gums together in order to achieve a particular therapeutic effect that cannot be mixed until the time of use.
There are various types of dispensers that have been used to dispense two or more non-compatible substances. For viscous materials these primarily include tubes and rigid pump dispensers. Illustrative of tube dispensers developed for this purpose are those described in U.S. Pat. No. 1,363,064; U.S. Pat. No. 1,698,404; U.S. Pat. No. 1,699,532; U.S. Pat. No. 2,819,723; and U.S. Pat. No. 3,105,615. In U.S. Pat. No. 1,353,064 there is disclosed side-by-side tubes, two tubes with a longitudinal separatory wall and two tubes created by a horizontal barrier with an opening at each end. U.S. Pat. No. 1,698,404 discloses a tube within a tube. In U.S. Pat. No. 1,699,532 there is shown a variation of a tube within a tube. In U.S. Pat. No. 2,819,723 there is shown a hair dying apparatus consisting of a dispensing comb and brush connected to a two tubes. In U.S. Pat. No. 3,105,615 there is shown a pair of side-by-side aligned tubes.
Another type of multi-chamber dispenser is the rigid pump dispenser. This type of dispenser is illustrated by U.S. Pat. No. 4,040,420; U.S. Pat. No. 4,046,288; U.S. Pat. No. 4,121,739; U.S. Pat. No. 4,747,517; U.S. Pat. No. 4,949,873; U.S. Pat. No. 5,020,694 and U.S. Pat. No. 5,056,906. U.S. Pat. No. 4,040,420 discloses a dual chamber device with two essentially cylindrical cylinders and hand actuated piston rods that separately move the pistons. The product converges at the exit and is co-dispensed. U.S. Pat. No. 4,046,288 discloses a related device where the pistons are moved on threaded piston rods. In U.S. Pat. No. 4,121,739 there is disclosed a particular seal construction on the pistons in a pump dispenser. In U.S. Pat. No. 4,747,517 the two pistons are described to be hemispherical. Related semicircular pistons are shown in U.S. Pat. No. 4,949,873. U.S. Pat. No. 5,020,694 discloses a dispenser where there is added structure to cause the dispensed substances to flow together. In related U.S. Pat. No. 5,395,827 there is disclosed a dual chamber dispenser that is adapted to use refill chambers. These various references illustrate the present state-of-the-art of multi-chamber dispensers, and in particular multi-chamber dispensers and refillable multi-chamber dispensers.
Each of these prior art dispensers has some problems. The tube dispensers do not guarantee a constant flow of each substance. If one tube is squeezed with more force than the other, more of the substance in that tube will be dispensed. This is a significant drawback. In the rigid dispensers the dispenser must be refillable. If not refillable there will be too much waste of plastic packaging. And some units that are refillable do not conserve the use of plastic. In U.S. Pat. No. 5,289,949 the entire top piece that includes a shroud, nozzle and closure are discarded and replaced. Only the lower housing with the piston rods is retained. This conserves little of the plastic of the dispenser.
The present dispenser addresses these issues and solves these problems. The two or more substances are dispensed in given amounts. The only components that are discarded after use are the chambers that contained the substances that have been dispensed. All of the other components are reused. Also, the flow path from the chambers to the dispenser exit is shortened. Pistons with a deformable upper surface are used to more fully expel all of the substances from the chambers. Other features include stabilized piston rods and the automatic puncturing of the seal on the refill chambers when the refill unit is inserted into the dispenser. A cutter located in the upper portion of the dispenser cuts the seal on the chambers and rolls the seal outwardly so that remnants of the seal will not affect the dispensing of the substances. This is automatically accomplished as the set of refill chambers is inserted into the dispenser.